The pre-harvest spouting risk for a suite of new wheat varieties was discussed at the 2019 Grains Research and Development Corporation (GRDC) Grains Research Update.

Pre-harvest sprouting has been a challenge for some growers in recent years, particularly on the south coast, which can result in quality and profit downgrades.

The WA Department of Primary Industries and Regional Development, with support from the GRDC, undertakes extensive laboratory testing, field trials and uses a rainfall simulator to evaluate the sprouting risk for key varieties and advanced breeding lines.

The Falling Number test is used to determine pre-harvest sprouting damage.

Research officer Jeremy Curry said the department has developed a Falling Number Index (FNI) with a 1-9 scale to rate the risk of a variety exhibiting a low falling number (FN).

The lower the FNI value the higher risk of sprouting and not meeting the minimum Falling Number receival standard.

“When a variety exhibits low falling number, it is generally associated with pre-harvest sprouting,” he said.

“However, the risk of low FN is complex and is the result not only of the genetics of the variety and environmental conditions at harvest but also the environmental conditions at particular growth stages.”

A total of 24 wheat varieties were evaluated at the department’s Esperance Research Facility in 2018, including recently released varieties, advanced breeding lines and control varieties.

“The highest rated variety was DS Pascal (FNI rating of 7), which has shown a very low risk of delivery with low falling number, primarily due to its grain dormancy,” he said.

Of the newer varieties, Tungsten and LRPB Havoc had a FNI rating of 3, which suggests a lower tolerance to pre-harvest sprouting and a risk to growers in susceptible areas.

The recently released variety Devil performed well in yield trials, although preliminary results suggest it will be a higher risk of low falling number than Scepter and Mace.

Mr Curry said growers considering planting new varieties in 2019 should assess the FNI and the sprouting risk in their location before sowing extensive areas.

“Just as with disease ratings, risk of pre-harvest sprouting is just another factor to take into account when thinking of adopting a new variety and we don’t know how these new varieties will compare until they have been extensively tested,” he said.

“It is useful to compare these ratings to the widely sown varieties Mace and Scepter, which both have a FNI of 5, suggesting a reasonable resistance to PHS, which has enabled their widespread adoption, even in high risk areas.”

While the new noodle wheats Kinsei and Ninja recorded a FNI of 4, the same as the popular noodle variety Calingiri, subtle differences were observed suggesting a slightly lower risk of sprouting, and an improvement compared to the high-yielding noodle wheat, Zen.

Mr Curry said a number of varieties showed a risk of low FN when sampled at physiological maturity, prior to exposure to significant rainfall.

“These responses haven’t occurred in every season or sowing time and so are driven by some interaction with the environment,” he said.

“There are a number of causes of low FN in the absence of rainfall, but these varieties may have a higher risk of low FN, simply due to their lower starting FN.”

The Falling Number Index for all Western Australian wheats is available in the department’s 2019 Wheat variety sowing guide for Western Australia, which is available online.